318i soft brake pedal

Post Thu Apr 25, 2013 2:16 pm

hey guys
so finish my 30 for the summer

gone to take her for a quick drive and the brake pedal seems too have a lot of travel and a bit soft
i put 2 new rear wheel cylinders on and have bled the whole system twice.
any ideas on what i could do next?
someone told me to pull the servo forward and adjust something behind there to get rid of some of the travel?
thanks
david

Post Thu Apr 25, 2013 7:16 pm

There is a pull rod that goes across the car behind the heater box. It screws into a clevis at each end, but one end has a normal right hand thread, while the other has a left hand thread, so turning it adjusts its length. There are flats on the bar for a 7(?)mm spanner near where it passes the clutch pedal. Slacken off the locknut, and adjust the rod until the brakke pedal is just short of its upper stop.
A long pedal can also be caused or contributed to by failing rubber flexible hoses (see if any swell when pushing the pedal hard with the engine on), play in the front wheel bearings, warped front discs, or a non working handbrake automatic adjuster (how much thread is showing in front of the adjuster nuts at the handbrake?).
It can also help to wait for several hours between initial and subsequent bleeding sessions, to allow very small bubbles in the fluid to collect together to form bigger bubbles which will bleed out.
Finaly, do you have ABS?

Post Thu Apr 25, 2013 10:13 pm

Mine has has one of the symptoms you describe Brian, if I press the pedal hard when engine is running and even the first pressing after shutting it down, I can hear a sound like I was pumping a bike tire. Are these the rubber hoses? What ones?
If I pump the brake pedal several times and fast with engine running, it starts to run rough like there was a lean condition.

Post Thu Apr 25, 2013 11:16 pm

DaniTD wrote:Mine has has one of the symptoms you describe Brian, if I press the pedal hard when engine is running and even the first pressing after shutting it down, I can hear a sound like I was pumping a bike tire. Are these the rubber hoses? What ones?
If I pump the brake pedal several times and fast with engine running, it starts to run rough like there was a lean condition.

All as it should be. Perfectly normal.
Just the sound of air being admitted into the inlet manifold via the brake servo.
The brakes are only normally operated when the engine is on over run (you don't normally press the brake pedal and accelerator together) when there is plenty enough vacuum to not affect the engine running.

Post Mon Apr 29, 2013 8:02 pm

Assuming your brakes are bled properly, then Brian has it right. You need to adjust your clevis (push rod to brake booster) and there is a section Bentley manual discussing. It is a tight area to work in, but can be done with some fiddling. It helps to be small and have small hands for this one. Good luck.

-Marc

Post Mon Apr 29, 2013 9:31 pm

mcaden wrote:Assuming your brakes are bled properly, then Brian has it right. You need to adjust your clevis (push rod to brake booster) and there is a section Bentley manual discussing.

Not in the UK! Bentley is for US spec. LH drive stuff. The adjustment on RH drive cars is on the pull rod that crosses inside the car behind the heater box.
LH drive cars don't have this rod and associated bell cranks, of course, and rarely need adjusting, since there's far less to wear.